JP3703530B2 - Hard substrate coater - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a hard substrate coating apparatus that is used for manufacturing a liquid crystal display panel or the like using a glass substrate and applies a coating solution such as a photoresist thinly and uniformly on a hard substrate.
[0002]
[Prior art]
In the manufacturing process of the liquid crystal plate, there is a process in which a coating solution such as a photoresist is thinly and uniformly applied to a hard substrate such as a glass substrate. For example, in the manufacture of a color liquid crystal plate, a red color mosaic solution having a photoresist function is uniformly applied to a glass substrate on which a transparent electrode has been previously formed, and then the color mosaic corresponding to red is cured by exposure. And removing the excess liquid to form a red color mosaic. Similar processing is repeated for other colors such as green and blue. Thus, when applying the coating liquid used as a photoresist, this liquid needs to be strictly controlled to a uniform thickness (for example, about 2 μ ± 5%) and applied thinly. This is because if the thickness of the coating is not uniform, unevenness of light transmittance occurs, resulting in deterioration of quality.
[0003]
Conventionally, a spin coater has been used for this coating. In this spin coater, a coating liquid is dropped near the rotation center of a rotated substrate, and the liquid is applied by scattering using a centrifugal force. However, this method using a spin coater not only deteriorates the labor efficiency in replacing the substrate, but also increases the amount of liquid that is scattered and discarded. For this reason, there was a problem that the cost was increased.
[0004]
In view of this, it is considered to use a device for applying the substrate by sandwiching the substrate between a pair of upper and lower rollers arranged horizontally. In this device, the lower part of the micro rod bar, which is the lower roller, is immersed in the coating liquid, and the substrate is sandwiched between the micro rod bar and the nip roller located above the micro rod bar, and then sent to the lower surface of the substrate by the micro rod bar. It is something to apply.
[0005]
[Problems of the prior art]
However, this method has a problem that the coating thickness becomes non-uniform when the front and rear edges of the hard substrate are bent. FIG. 8 is an enlarged view schematically showing a main part of the coating apparatus, and FIG. 9 is a plan view of a hard substrate for explaining a coating finish state. In FIG. 8, reference numeral 10 denotes a glass substrate used for a color filter of a liquid crystal plate, which is a hard substrate. The glass substrate 10 has, for example, a width of 300 to 500 mm, a length of 400 to 600 mm, and a thickness of 0.7 mm.
[0006]
12 is a coating liquid tank, and 14 is a microrod bar. The micro rod bar 14 is formed by winding a thin metal wire in close contact with the surface of a rod having a circular cross section, and applies a liquid by utilizing a capillary phenomenon caused by a groove between the metal wires. The micro rod bar 14 is driven by a motor while being placed on a backup material 16 provided in the coating solution tank 12.
[0007]
The liquid level of the coating liquid 18 is controlled so that the lower part of the microrod bar 14 is sufficiently immersed. The outer diameter (diameter) of the micro rod bar bar 14 is about 12 mm. Reference numeral 20 denotes a nip roller, which is rotatably held above the micro rod bar 14 while maintaining a predetermined gap.
[0008]
The glass substrate 10 is transported from the left side of FIG. 8 with both left and right edges placed on the transport rollers, and the front edge enters between the micro rod bar 14 and the nip roller 20. Thereafter, the nip roller 20 and the micro rod bar 14 are rotated to the right side at a constant speed, and the liquid is applied to the lower surface of the glass substrate 10 by the micro rod bar 14 during that time.
[0009]
In FIG. 8, an alternate long and short dash line A is a movement trajectory of the lower surface when the glass substrate 10 moves while being in contact with the microrod bar 14, and is hereinafter referred to as a normal lower surface position A. When the lower surface of the glass substrate 10 is sandwiched between the microrod bar 14 and the nip roller 20, it moves on the regular lower surface position A at a constant speed, so that the uniformity of the coating thickness is also improved. 10A shows the position of the glass substrate 10 at this time.
[0010]
However, when the glass substrate 10 is thin as described above, the front edge of the glass substrate 10 bends so as to bend downward before entering the microrod bar. This is because the glass substrate 10 is transported in a state where only the left and right edges are placed on the transport roller and the central portion is floated. 8B in FIG. 8 shows a position near the center of the front edge of the glass substrate 10 at this time.
[0011]
The amount of bending a, that is, the amount of descent relative to the normal lower surface position A near the center of the front edge, is remarkably increased depending on the size of the glass substrate 10. For example, when the thickness is 1.1 mm, the amount of deflection is sufficiently small, but when the thickness is 0.7 mm and the width × length is 300 × 400 (mm), about 0.8 mm, 400 × 500 (mm) It is about 2.4 mm in the case of the one and about 5.3 mm in the case of the 500 × 600 mm. Since the weight increases as the width and length increase, the amount of deflection a also increases rapidly.
[0012]
When the front edge central portion of the glass substrate 10 is lowered, the front edge comes into contact with the rotating microrod bar 14 as shown in FIG. During this time, a larger amount of liquid is accumulated on the lower surface near the center of the front edge of the glass substrate 10 than on both sides. Therefore, there is a problem that the coating thickness in the hatched area indicated by B in FIG. 9 is increased.
[0013]
Similarly, when the rear edge of the glass substrate 10 escapes from the gap between the microrod bar 14 and the nip roller 20, the vicinity of the center of the rear edge bends downward. For this reason, the most lowered portion near the center of the trailing edge contacts the cough 12A (FIG. 8) on the outlet side of the coating liquid tank 12. As a result, the coating solution near the center of the rear edge of the glass substrate 10 is peeled off and becomes thin. A hatched area indicated by C in FIG. 9 indicates an area in contact with the cough 12A near the center of the trailing edge. In addition, uncoated areas D and E are provided on both side edges of the glass substrate 10, and these areas D and E are placed on the conveyance roller.
[0014]
OBJECT OF THE INVENTION
The present invention has been made in view of such circumstances, and a hard substrate coating apparatus capable of preventing the coating thickness in the vicinity of the center of the front edge of the hard substrate from becoming thicker than both sides and applying the uniform coating thickness. The first purpose is to provide it. A second object of the present invention is to provide a hard substrate coating apparatus capable of preventing the vicinity of the center of the rear edge of the hard substrate from contacting the cough on the outlet side of the coating liquid tank so that the coating can be applied with a uniform coating thickness. .
[0015]
[Structure of the invention]
According to the present invention, a first object is to send a hard substrate sandwiched between a microrod bar whose lower part is immersed in a coating liquid tank and a nip roller disposed above the microrod bar. In the hard substrate coating apparatus for applying a coating liquid to the lower surface of the hard substrate, the hard substrate extends obliquely from the hard substrate entry side of the micro rod bar toward the micro rod bar, and the tip of the hard substrate is the micro rod. A hard substrate coating apparatus, wherein a push-up member that is positioned below a movement trajectory of the lower surface when moving while contacting a bar and restricts bending of the front edge of the hard substrate is fixed to the coating liquid tank , Is achieved.
[0016]
Here, one push-up member can be provided near the center in the width direction of the front edge of the hard substrate, but a plurality of push-up members may be provided. For example, when the width of the hard substrate is wide, even if only the central part in the width direction is pushed up by the push-up member, both sides of the board are bent downward, and the amount of bending is increased. In such a case, it is desirable to provide a plurality of push-up members.
[0017]
When the hard substrate is supported by one push-up member, it is desirable to have one contact point located at the center of the front edge of the hard substrate at the tip. The contact point is preferably about 6 mm away from the center of the microrod bar and about 0.4 mm below the normal bottom surface position A with respect to the coating apparatus and glass substrate described in FIG.
[0018]
The second object can be achieved by providing another lifting member substantially similar to the lifting member on the hard substrate escape side of the microrod bar. In this case, since the liquid has already been applied to the lower surface of the hard substrate 10, the contact point should be about 1.0 mm below the regular lower surface position A under the same conditions as in FIG.
[0019]
Embodiment
FIG. 1 is an overall layout view of an embodiment of the present invention, FIG. 2 is a perspective view of an essential part thereof, FIG. 3 is a partially exploded perspective view of FIG. 4, and FIG. FIG. 5, FIG. 5 is a plan view (A) and a side view (B) perspective view (C) of the push-up member on the entry side, FIG. 6 is a view showing a state immediately before entering the glass substrate, and FIG. FIG.
[0020]
In these drawings, the same parts as those in FIG. 7 are denoted by the same reference numerals, and the description thereof will not be repeated. 1 and 2, reference numeral 22 denotes a conveyance roller that contacts only the lower surfaces of the left and right edges of the glass substrate 10. The transport roller 22 is driven by a drive mechanism housed in the case 24 shown in FIG. 2, and transports the glass substrate 10 at a constant speed.
[0021]
As shown in FIG. 2, the coating liquid tank 12 has a long and shallow liquid reservoir portion 26 in a direction orthogonal to the feeding direction of the substrate 10, and a new liquid is supplied to the liquid reservoir portion 26 from a liquid supply pipe. The coating solution is discharged from the drain port. The liquid level of the coating liquid is monitored by a liquid level sensor (not shown) and is always managed at a constant level.
[0022]
The micro rod bar 14 is held horizontally so that the upper part thereof is exposed from the liquid. Further, an intermediate portion of the microrod bar 14 is supported from below by a backup member 16 shown in FIG. The backup member 16 is made of a hard synthetic resin having excellent slidability, and a semicircular groove formed on the upper surface along the longitudinal direction comes into contact with the microrod bar 16 from below, and the microrod bar 14 This is to prevent the deflection. The height of the backup member 16 can be finely adjusted from the lower surface of the coating solution tank 12 by a large number of adjusting screws 28 arranged below the backup member 16.
[0023]
One end (end on the back side in FIG. 1) of the micro rod bar 14 protrudes rearward from the coating solution tank 12, and this protruding end is connected to an electric motor (not shown) by a detachable joint 30 (FIG. 3). Yes. The rotation of the electric motor is also transmitted to the conveying roller 22 so that the feeding speed of the glass substrate 10 is equal to the conveying speed of the conveying roller 22. The surface of the nip roller 20 is made of conductive rubber, and is held so as to apply a predetermined clamping pressure to the glass substrate 10 with the glass substrate 10 sandwiched between the microrod bar 14.
[0024]
3 and 4, 32 is an entry side push-up member, and 34 is an escape side push-up member. These push-up members 32 and 34 are fixed to grooves 36 and 38 formed near the center of the application range and outside the liquid reservoir 26 of the application liquid tank 12. That is, as shown in FIG. 5, the entry side push-up member 32 has a base portion 32a fitted in the groove 36 and a tongue portion 32b extending obliquely upward from the upper surface thereof, and is made of duralumin or stainless steel.
[0025]
As shown in FIGS. 4 and 5, the base portion 32a is formed with four loading chambers 32c for loading balls and springs for pressing the inner surface of the groove 36, while adjusting screws 40, 40 (FIG. 5) are formed from above. ) Is screwed in. As a result, when the base portion 32a is engaged with the groove 36, the ball presses the inner surface of the groove 32 to fix the base portion 32a, while the heights of the base portion 32a and the tongue portion 32b can be adjusted by the adjusting screws 40 and 40.
[0026]
The tip of the tongue 32b is a contact point 32d. As shown in FIG. 4, the contact point 32 d is about 6 mm away from the center of the microrod bar 14 toward the entrance side of the substrate 10, and its height is set to be lower than the normal lower surface position A by about 0.4 mm.
[0027]
The escape-side push-up member 34 has substantially the same configuration as the entry-side push-up member 32, and therefore description thereof will not be repeated. The escape side push-up member 34 has a base 34 a fixed to the groove 38 and a tongue 34 b extending obliquely upward toward the micro rod bar 14. The tip of the tongue 34b is a contact point 34c, which is about 6 mm away from the center of the microrod bar 14 and about 1.0 mm below the normal lower surface position A. The contact point 34c and the vicinity of the tip of the tongue 34b are preferably coated with a material that repels the liquid, for example, Teflon (registered trademark) because the coating liquid of the glass substrate 10 adheres thereto.
[0028]
Next, the operation of this embodiment will be described. The glass substrate 10 fed from the left side to the right side in FIGS. 1 and 2 by the transport roller 22 enters between the microrod bar 14 and the nip roller 20. At this time, since the left and right edges of the glass substrate 10 are supported by the transport rollers 22, the vicinity of the center in the width direction is bent downward by the weight of the glass substrate 10 itself. However, when the front edge central portion of the glass substrate 10 comes into contact with the tongue portion 32b of the entry side push-up member 32, its lowering is restricted.
[0029]
For this reason, the amount of deflection of the central portion of the front edge of the glass substrate 10 is limited by the contact point 32d. FIG. 6 shows this state. In this way, the front edge of the glass substrate 10 enters between the microrod bar 14 and the nip roller 20 while the amount of bending is limited.
[0030]
Thus, when the front end (front edge) of the glass substrate 10 is sandwiched between the nip roller 20 and the micro rod bar 14, the front end portion of the glass substrate 10 becomes completely flat (horizontal). That is, the glass substrate 10 is sent on the regular lower surface position A. For this reason, the vicinity of the center of the glass substrate 10 is in a state of being lifted 0.4 mm from the contact point 32d. As a result, the glass substrate 10 is in contact with the contact point 32d within a range within 6 mm from the tip edge.
[0031]
Further, since the amount of deflection near the center of the front edge of the glass substrate 10 is limited to 0.4 mm, the width and length of the thick coating region B (see FIG. 9) formed near the center of the front edge of the glass substrate 10 (see FIG. 9). The length of the glass substrate 10 in the feeding direction) becomes extremely small, and a practically uniform coating thickness can be obtained.
[0032]
Since the coating liquid 28 of the liquid reservoir 26 is attached to the surface of the microrod bar 14 by the rotation, the coating liquid is applied to the lower surface of the glass substrate 10 as the microrod bar 14 rotates. During application, a certain amount of application liquid (meniscus) R is held at the corner between the entry side of the substrate 10 and the microrod bar 14 (FIG. 7). Since the level of the liquid surface of the liquid reservoir 26 and the clamping pressure by the nip roller 20 are controlled to be constant, the thickness of the liquid applied to the lower surface of the glass substrate 10 can be sufficiently thin and managed with high accuracy. .
[0033]
When the glass substrate 10 is detached from the microrod bar 14, the central portion of the rear edge of the glass substrate 10 bends downward, but the rear edge of the glass substrate 10 contacts the contact point 34c of the escape side push-up member 34. The amount of deflection is limited. For this reason, when the center part of the rear edge of the glass substrate 10 moves away from the surface of the microrod bar 14, the distance that descends becomes short, and the vicinity of the center of the rear edge of the glass substrate 10 contacts the cough 12A of the coating liquid tank 12. Disappear.
[0034]
Accordingly, there is no region C where the trailing edge of the glass substrate 10 comes into contact with the weir 12A and the coating solution is peeled off from the glass substrate 10, and only one stripe having a length of 6 mm can be formed by contact with the contact point 34c. The contact streaks disappear almost completely if the coating solution that has adhered to the rear end of the glass substrate 10 in the subsequent process is sucked by the suction device. For example, if the suction device sucks the thick-coated portion from about 5 mm before the rear edge of the glass substrate 10, the influence of the contact stripe does not become a practical problem.
[0035]
Generally, the thick coating regions B and C formed on the front edge and the rear edge of the glass substrate 10 are considered to be inconvenient if they are within 10 mm from the front edge and the rear edge. Therefore, it is desirable that the contact point 34c of the push-up member 34 on the escape side is separated from the center of the microrod bar 14 by about 6 mm.
[0036]
In the above embodiment, the shape of the tongue portions 32b and 34b of the push-up members 32 and 34 on the entry side and the escape side is a pointed tip in a triangular shape, but instead of this, a virtual line is shown in FIG. It is good also as a rectangular type as shown by and a pipe shape.
[0037]
In the push-up member 32 on the entry side, it is desirable that the tip of the tongue portion 32b is pointed like a needle and positioned at the center of the front edge of the glass substrate 10. This is because there is no possibility that the resistance when the tongue 32b hits the front edge of the glass substrate 10 will tilt the glass substrate 10 on the horizontal plane. Needless to say, the push-up members 32 and 34 may be formed integrally with the coating solution tank 12. Further, screws may be directly attached to the coating solution tank 12.
[0038]
【The invention's effect】
As described above, the invention according to claim 1 is provided with a push-up member that faces the lower front edge of the hard substrate and limits the amount of bending of the hard substrate front edge downward. The paint area can be narrowed.
[0039]
One push-up member may be provided at the center in the width direction of the front edge of the hard substrate, but a plurality of push-up members may be provided. When one push-up member is used, if one contact point is provided so as to be in contact with the center of the front edge of the hard substrate, the hard substrate is caused by the resistance when the front edge of the hard substrate contacts the push-up member. Does not tilt (claim 2).
[0040]
When a microrod bar having a diameter of about 12 mm is applied to a glass substrate for a liquid crystal plate having a thickness of about 0.7 mm and a width of about 500 mm, this contact point is 0.4 mm below the normal bottom surface position and is microscopic. It is desirable to keep about 6 mm away from the center of the rod bar.
[0041]
According to the invention of claim 4, the amount of downward deflection when the trailing edge of the hard substrate is separated from the micro rod bar is limited by the escape side push-up member. For this reason, it is possible to prevent the vicinity of the center of the rear edge of the hard substrate from coming into contact with the cough of the coating liquid tank. When applying to the glass substrate under the same conditions as described above, the contact point of the escape side push-up member should be set at a position about 6 mm away from the microrod bar and about 1.0 mm lower than the normal bottom surface position. Good (Claim 5).
[Brief description of the drawings]
FIG. 1 is an overall layout view of an embodiment of the present invention. FIG. 2 is an enlarged perspective view of the coating part. FIG. 3 is a perspective view of a coating liquid tank. Top view (A), side view (B), and perspective view (C) of the entry side push-up member
FIG. 6 is a view showing a glass substrate being entered. FIG. 7 is a view showing a glass substrate being applied. FIG. 8 is a cross-sectional view of a coating portion for explaining the disadvantages of the conventional method. Bottom view of glass substrate to explain the properties [Explanation of symbols]
10 Glass substrate (hard substrate)
12 coating liquid tank 14 micro rod bar 18 nip roller 22 transport roller 32 entry side push-up member 34 escape side push-up member 32d, 34c contact point A regular bottom surface position B thick coating region C on the leading edge side contact region on the trailing edge side

Claims (5)

The coating liquid is applied to the lower surface of the hard substrate by sending the hard substrate sandwiched between a microrod bar whose lower part is immersed in the coating liquid tank and a nip roller disposed above the microrod bar. In the hard substrate coating apparatus, the tip of the micro rod bar extends obliquely from the hard substrate entrance side toward the micro rod bar, and the tip of the micro rod bar is a lower surface when the hard substrate moves while contacting the micro rod bar. A hard substrate coating apparatus, wherein a push-up member that is positioned below a movement locus and restricts bending of a leading edge of a hard substrate is fixed to the coating liquid tank .   2. The hard substrate coating apparatus according to claim 1, wherein the push-up member has one contact point positioned at the center in the width direction of the front edge of the hard substrate.   The hard substrate is a glass substrate having a thickness of 0.7 mm and a leading edge width of 500 mm, the microrod bar has a diameter of about 12 mm, the contact point at the tip of the push-up member is about 6 mm away from the center of the microrod bar, and The hard substrate coating apparatus according to claim 2, wherein the hard substrate coating device is provided at a position in contact with the lower surface of the front edge of the hard substrate in a state where the vicinity of the center of the front edge of the hard substrate is bent downward by about 0.4 mm. The coating liquid is applied to the lower surface of the hard substrate by sending the hard substrate sandwiched between a microrod bar whose lower part is immersed in the coating liquid tank and a nip roller disposed above the microrod bar. In the hard substrate coating apparatus, the bottom surface of the microrod bar extends from the hard substrate escape side obliquely upward toward the microrod bar toward the microrod bar when the hard substrate moves while contacting the microrod bar. A hard substrate coating apparatus comprising a push-up member that is positioned below the movement locus and that restricts bending of the trailing edge of the hard substrate.   The hard substrate is a glass substrate having a thickness of 0.7 mm and a trailing edge width of 500 mm, the microrod bar is about 12 mm in diameter, and the lifting member is about 6 mm away from the center of the microrod bar and near the center of the trailing edge of the hard substrate 5. The hard substrate coating apparatus according to claim 4, having one contact point that contacts the lower surface of the rear edge of the hard substrate while being bent downward by about 1.0 mm.

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